// 基本样式
* {
    margin: 0;
    padding: 0;
}

li {
    list-style: none;
}

a {
    text-decoration: none;
    color: black;
}

// 版心
.w {
    width: 1200px;
    margin: 0 auto;
}

// 顶部导航栏
.top {
    display: flex;
    justify-content: space-between;
    color: #000;
    height: 45px;
    background-color: rgba(255, 255, 255, 0.7);
    box-shadow: 0 0 15px #747474;
    position: fixed;
    width: 100vw;

    .logo {
        width: 8vw;
        background-color: #422f2f;
        color: white;
        text-align: center;
        line-height: 35px;
        border-radius: 20px;
        margin: 5px;
    }

    .nav {
        width: 30vw;
    }
}
// 内容
.null_box{
    height: 70px;
}
.box{
    width: 860px;
    background-color: rgba(255, 255, 255, 0.5);
    box-shadow: 0 8px 25px 0 rgba(148, 146, 146, 0.7);
    margin: 0 auto;
    padding: 45px;
}
.box:hover {
    box-shadow: 0 8px 25px 0 rgba(0, 0, 0, 0.7);
    transition: all .5s;
}

pre{
    background-color:#efefef;
}